The present invention is related to a display utilizing cholesterin liquid crystal polymer for enhancing contrast, and more particularly to a display with self-luminous cell. The display includes a lighting layer having cholesterin liquid crystal phase. The lighting layer goes through backfire and is arranged into planer structure to induce and emit manual circular polarized light. The lighting layer cooperates with a circular polarizing optical coating to enhance the contrast and brightness of the display.
The conventional lightweight and small-sized display with self-luminous cell has wider vision angle. Such display can be made on a soft substrate. FIG. 5 shows the structure of the self-luminous cell. An ITO bus-bar 81 is overlaid on a transparent substrate 8. An electric hole conductive layer 82 is overlaid on the ITO bus-bar 81. A lighting layer 83 is overlaid on the electric hole conductive layer 82. An electronic conductive layer 84 is overlaid on the lighting layer 83. A cathode electrode layer 85 is overlaid on the electronic conductive layer 84. An insulating packaging layer (not shown) is disposed on the cathode electrode layer 85. When a circuit supplies driving current to the display, by means of the lighting layer 83, the self-luminous cell emits light.
The cathode electrode layer 85 is a metal layer forming a mirror face that tends to reflect the incident light A of the environment as shown in FIG. 6. Accordingly, when the display panel is used outdoors in brighter environment, the cathode electrode layer 85 will reflect the incident light to form environmental reflected light B. The reflected light B will interfere with and affect the displaying effect of the display panel. To solve this problem, generally a black cathode is used. Alternatively, a black layer is disposed between the cathode electrode layer 85 and the lighting layer 83 for absorbing light. Still alternatively, a quarter wavelength phase difference plate or circular polarizing optical coating is laid on the cell to eliminate the interference of the light reflected by the cathode electrode layer 85. However, the reliability of the black cathode will decline with time. With respect to the black layer, the development of the material and practical effect of such material have not yet matured. The phase difference plate utilizes light travel difference of the reflected light to destructively interfere with and eliminate the light. Such measure requires precise control of the distance between the phase difference plate and the cathode electrode layer 85 for eliminating the reflected light. It is quite difficult to perform the manufacturing procedure. Moreover, such measure can hardly cover all visible light wavelengths.
In addition, with respect to the circular polarizing optical coating, the manual circular polarized light in one direction (such as levorotary light) of the environmental incident light will be absorbed by the circular polarizing optical coating, while the manual circular polarized light in another direction (such as dextrorotary light) of the environmental incident light is permitted to penetrate through the circular polarizing optical coating. The penetrating dextrorotary light is reflected by the cathode electrode layer 85 to form levorotary light. When passing through the circular polarizing optical coating, the reflected levorotary light will be further absorbed by the circular polarizing optical coating. Therefore, the cathode reflection interference of the environmental intense light will be eliminated. However, the circular polarizing optical coating will absorb the manual circular polarized light in one direction of the incident light. Therefore, in general, 50% of the light emitted from the self-luminous cell will be also absorbed so that the brightness of the self-luminous cell will be half reduced. This greatly reduces the using efficiency of energy.